This invention provides a cost-effective methodology to measure the mass concentration of impurities in the air resulting from the exhaust of a combustion system such as diesel and gasoline engines used in the automotive industry. This methodology can also be used to measure any particulates in gas streams used in industry. It is drastically different from the conventional methods that are currently used by the automotive companies in monitoring particulates emissions. The invention can also be used to detect and/or identify and/or measure pollutants in ambient air.
Test data have shown that the average sizes of particulates from the exhaust of combustion systems are in the order of nanometers, or 10−9 meter, which are invisible but can be harmful when inhaled. The Environmental Protection Agency (EPA) has established strict regulations on the level of mass concentration of particulates discharged from the exhaust of combustion systems in order to reduce air pollution. The allowable level of particulates decreases every year as the demand on pollution control increases.
The conventional way of measuring the level of particulates concentration is to use a special filter to collect the residuals of the exhaust gases through a diluted chamber over certain period of time, and then weigh them on an electronic micro-scale inside a clean room. The equipment and facilities involved can be extremely expensive and the whole process can be very time consuming.
Quality of breathing air is an important health issue. While EPA has established outdoor air quality standards on ozone and particulates, no indoor air quality standards have been established except for the well known contaminants, such as Radon, as there are too many possible indoor air pollutants. Most people spend up to 90% of their time indoors. Although air contaminants in a private home may be limited to the owner's concern, air quality in office buildings, public transportations, theaters, stores, etc. is a public health issue. While it is possible that contaminated air in the outdoors manages to get inside a building, the source of air contamination is often found inside a building. Tobacco smoke, fungi, carbon monoxide, vapor from paint and carpet glue, and communication cables are well known sources of air pollution, but oftentimes the sensors are people who complain of nausea, headaches, red eyes, and dry mouths, many of which are dismissed as subjective sensations instead of serious illnesses. Thus, there is a need to be able to quantitatively detect the presence of various forms of air pollutants in a closed environment both timely and inexpensively. Such a sensor will be useful to locate the source of contaminations as well.
There are currently a number of airborne particle counters and toxin detectors available in the market, some of which are costly and require experienced operators.